This invention relates generally to corrosion protection for electronic components, and more particularly to a method for passivating hybrid microelectronic devices with a plasma polymerized layer.
The electronics industry is continuously striving to prevent corrosion of microelectronic devices. This is especially true in hybrid devices which use a wide variety of construction materials. Attempts to passivate these types of circuits include total encapsulation with silicone compounds and surface passivation with silicone oxides or silicone nitrides. U.S. Pat. No. 4,163,072 issued to Soos, and U.S. Pat. No. 4,059,708 issued to Heiss, Jr. et al are illustrative of these methods.
Microelectronic devices for military use are subjected to stringent mechanical and environmental tests during various stages of their fabrication. These hybrid devices usually contain thin metallic film circuitry and discrete components such as capacitors, transistors and diodes bonded to the circuitry. These hybrid devices must be sealed to protect the internal components from exposure to moisture and other environmental agents which can degrade the microelectronics.
Presently, military hybrid devices are most often hermetically sealed by glass seals, soldering or welding all of which are rather costly processes. Furthermore, hybrid devices sealed by these methods are usually not easily, nor inexpensively, reopened if repair to interior parts becomes necessary.
Since most hybrid devices for military use are custom-made in small quantities, they are usually quite costly compared with their commercial counterparts. Thus, it becomes cost beneficial to repair a faulty military hybrid circuit rather than to scrap it. Such repairability requires that any passivating coating be easily removable.